Try doing these three strength-builders while you listen to music, take a break from studying, or while you watch TV.

1. Sit BacksSit on the floor with your legs extended in front of you, knees bent.Put your arms straight out in front of your chest.Gradually lean back, keeping your arms straight and your abs tightGo as far back as you can without laying downSlowly bring yourself back to the sitting positionRepeat 9 more timesAs you get better at it, add another set of 10, resting 30 seconds between the two sets.

2. Breathing ButterflyStand tall with your feet hip-distance apartLift your arms straight out to your sidesExhale as you lift your right knee across your body, bringing your left elbow down to meet itInhale and return to the arms-out positionSwitch legs/arms and repeat 9 more timesAs you get better at it, add another set of 10, resting 30 seconds between the two sets.

3. Chair SquatsPlace a chair behind you. Be sure it’s not a chair on rollersStand tall in front of the seatPut your arms straight out in front of you and slowly start to sit down in the seatStop before you sit down, then slowly straighten back up to standing.Repeat 9 more timesAs you get better at it, add another set of 10, resting 30 seconds between the two sets.